Currently, medical devices that are used for delivering nano/micro-particles of the drugs to a target site in a blood vessel include the Drug Eluting Balloons (DEBs), the Drug Eluting Stents (DESs) and the like. Generally, polymers are used along with the nano/micro-particles of the drugs for loading the nano/micro-particles of the drugs on the surfaces of the medical devices. However, the use of polymers is associated with several side effects. For example, the drug delivering medical devices with nano/micro-particles of the drug encapsulated with a polymer may produce inflammation at the target site. Further, because of improper degradation of the polymer, the drug may be delivered in an uncontrolled manner. In addition, a semi-degradation of polymers may result in the “knife effect” and the “edge effect”.
Usually while using the DESs, both the inner surface and the outer surface of the stent are coated with the drugs and the polymers. As the inner surface of the DESs carries the drug, the DESs are associated with delayed healing and improper healing of the affected area. The delayed healing and the improper healing may result in sub-acute thrombus formation and late thrombus formation. Additionally, most of the drugs that are administered to the blood vessel using the DEBs and the DESs have a lipophilicity insufficiency in achieving an in-tissue diffusion of the drugs. As a result, the existing DEBs and DESs are associated with the phenomenon of focal restenosis.
In order to avoid the side effects associated with the polymers, few non-polymeric approaches are also used in the art for loading the nano/micro-particles of the drugs on the surface of the DEBs and the DESs. However, the non-polymeric approaches are generally based on surface modification of the DEBs and the DESs. The surface modification approaches may not guarantee uniform distribution of the nano/micro-particles of the drugs across the affected area. This may further lead to improper healing and delayed healing of the affected area. Further, the non-polymeric approaches can be used only for loading and delivering certain highly lipophilic drugs like paclitaxel. Whereas, the relatively low lipophilic drugs like sirolimus may not be successfully loaded on the surface of the medical device and delivered there from using the non-polymeric approaches.
Therefore, there is a need in the art for an improved method of loading the drugs on the surface of insertable and/or implantable medical devices without using polymers and without modifying the surface of the insertable and/or implantable medical devices.